x86/efi: Add a wrapper function efi_map_region_fixed()

Kexec kernel will use saved runtime virtual mapping, so add a new
function efi_map_region_fixed() for directly mapping a md to md->virt.

The md is passed in from 1st kernel, the virtual addr is saved in
md->virt_addr.

Signed-off-by: Dave Young <dyoung@redhat.com>
Acked-by: Borislav Petkov <bp@suse.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

diff --cc arch/x86/include/asm/efi.h
Simple merge

diff --cc arch/x86/platform/efi/efi_32.c
Simple merge

diff --cc arch/x86/platform/efi/efi_64.c
Simple merge